Stimulation of human natural killer cytotoxicity and protection of mice from infection due to herpes simplex virus by recombinant human leukocyte interferon.

Destruction of virus-infected cells in the absence of antibody (natural killer cytotoxicity [NKC]) has been correlated with resistance to infection due to herpes simplex virus (HSV). Two preparations of human leukocyte interferon produced by recombinant DNA bacteria--IFLrA and IFLrD--were demonstrated to increase NKC in a dose-dependent fashion in vitro. IFLrA was more potent than was IFLrD in this assay. When administered intraperitoneally in combination with human leukocytes to one-week-old mice, IFLrA and IFLrD significantly increased survival (to 47.6% [P less than 0.01] and 23.8% [P less than 0.05], respectively) after an otherwise uniformly lethal challenge of HSV. Differences between interferon immunostimulating activities at similar antiviral concentrations may be important in vivo in animals and in clinical settings.